The present invention relates to measurement devices in general and more particularly to a weight measuring apparatus having both analog and digital output displays for displaying the weight of a user.
There exists in the prior art numerous methods and apparatus for measuring and displaying body weight. For example, various types of platform scales have been designed and manufactured by scale manufacturers. These scales include a conventional mechanical analog scale having a base and a platform movable relative to the base. A lever structure is movable with the platform for causing rotation of a dial. Angular rotation of the dial represents weight on the platform which is indicated by numerical indicia on the dial and is visible through a window in the platform. U.S. Pat. No. 5,141,065 entitled WEIGHT ACTIVATED PLATFORM SCALE issued Aug. 25, 1992 to Maxwell et al. discloses an electronic-mechanical version that replaces a rotary dial display with a digital readout. The dial forms part of an electrical encoder. As is conventionally understood, the encoder may take one of two known forms, namely a pulse count type which counts pulses representing angular movement, or an encoded type in which the dial is provided with a coded pattern. The coded pattern indicates angular position which is read by a sensor and converted to a measure of weight. Lastly, a strain gauge type scale includes a strain gauge for measuring pressure applied on the platform which is converted to an electrical signal applied to a digital readout.
While the prior art includes both mechanical analog scales as well as electronic digital scales for measuring and displaying a user""s weight, a need in the art exists to provide a user with the option to measure and view the measured weight through either digital or analog means.
The invention is embodied in a mechanical weighing scale having mechanical parts driving a pointer rotating around a fixed disc or dial having slots or holes formed therein. The mechanical pointer operates to provide an analog display of one""s weight to the user. An optical sensor system is responsive to the mechanical motion of the mechanically-rotating pointer as it passes over each of the holes or slots for determining a number of counts associated with the mechanical motion of the rotating pointer and translating the counts to a corresponding weight value for display onto a digital display. The optical sensor system includes a series of photo detectors placed underneath corresponding ones of the holes or slots, and operates for detecting when the pointer passes over a corresponding slot on the dial so as to trigger an electrical signal which functions as a pulse count to a microprocessor unit. Each time the pointer passes over a slot, a corresponding photo detector is triggered causing a pulse count to be sent to the microprocessor. When the pointer stops rotating, corresponding to a given weight value, the microprocessor totals the number of pulse counts and converts that to a digital weight representation. In this manner the scale has both a visual analog output indicated by the pointer""s angular position as well as a digital display output corresponding to the number of pulses sensed by the optical sensor system due to the rotating pointer.
Alternatively, the invention is embodied in a mechanical weighing scale having mechanical parts responsive to a weight disposed thereon for driving a rotatable shaft. A pointer coupled to the shaft rotates in accordance with the shaft about a fixed disk having indicia thereon for determining an analog representation of a user""s weight. A rotatable disc or wheel is also coupled to the rotatable shaft for rotating therewith. The disc or wheel includes slots or holes formed therein. An optical sensor disposed at a fixed position relative to the rotatable wheel operates to sense the mechanical rotation of the wheel via the slots or holes formed therein and determines a number of counts associated with the mechanical motion and translates the counts to a corresponding weight value for display onto a digital display via a digital processor. The optical sensor comprises a photo detector fixedly positioned relative to the rotating disc or wheel to detect wheel movement via the corresponding holes or slots thereon so as to trigger an electrical signal which functions as a pulse count to a microprocessor unit. Each time a slot on the disc passes over the photo detector, the detector is triggered causing a pulse count to be sent to the microprocessor. When the disc stops rotating, corresponding to a given weight value, the microprocessor totals the number of pulse counts and converts that to a digital weight representation for display.